1. Field of the Invention
The present invention relates to a triclinic structure composite oxide composed of zinc and tungsten, in particular, a phosphor widely used as a scintillation plate for detecting radiation, such as an electron beam and X-rays, and as various display devices.
2. Description of the Related Art
The tungstates (MnWO4, CoWO4, NiWO4, MgWO4, CdWO4, MnWO4 and the like) represented by a general formula XWO4 are widely used as optical materials, such as scintillator materials and laser materials. Among these tungstates, particularly notable is ZnWO4, where X=Zn. It is an optical material having a monoclinic structure referred to as SANMARTINITE, in which a tungsten atom is bonded to six oxygen atoms to form an octahedron. Its emission spectrum exhibits a broad blue-green light emission with a peak around 500 nm. This monoclinic system is the only structure represented by the formula ZnWO4.